Platinum group metal refining

ABSTRACT

A process for refining platinum group metals (PGM) first removes concentrations of base metals (BM) from the PGM through precipitation of the BM by increasing alkalinity in the dissolving aqueous solution. A large fraction of the aqueous solution is distilled before increasing alkalinity. Os is recovered from the distillate The aqueous solution is heated following precipitation of the BM; and the PGM is loaded on borane containing reduction resins. The loaded resins are washed; and the PGM is stripped from the resins with gaseous oxygen. The stripped PGM are then processed using only substituted quaternary ammonium salt (SQAS) as the refining reagent. The waste solutions from the refining are all combined together; solvent is removed; residual PGM is recycled in the process; and concentrated SQAS is recovered for further refining. Pt, Pd and Ru are refined from acidic SQAS solutions by reducing the metals from the solutions with H 2 .

RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application 61/798,723, filed Mar. 15, 2013, the disclosure of which is incorporated in its entirety herein by reference.

BACKGROUND OF THE INVENTION

The field of the present invention is the extraction and separation of platinum group metals.

The unique ability of substituted amine salts to refine platinum group metals (PGM singular and plural=Pt, Pd, Rh, Ru, Os, Ir) has been described in U.S. Pat. No. 7,935,173, the disclosure of which in its entirety is incorporated herein by reference. This patent employed the use of substituted quaternary ammonium salt (hereinafter SQAS singular and plural). The SQAS, are described by a general formula: H₀₋₃R₄₋₁NX where H=hydrogen, R=organic group, N=nitrogen and X=halide. Within that patent, reference was made to the many possible pathways to separating and purify PGM.

Boron containing resins, reported to load platinum, palladium, rhodium and iridium, are characterized in U.S. Pat. Nos. 4,223,173; 4,240,909; 4,311,812; 4,355,140; 4,410,665, the disclosures of which in their entirety are incorporated herein by reference. These borane containing resins load PGM as solid metal rather than as ions. The PGM ions are reduced to metals that cling to the organic backbone of the resin. Further, the loading capacity of these resins is a very high at 500-1000 grams/liter of resin. These resins are described in the aforementioned five patents as solid nonionic cross-linked resins containing amine or phosphine borane adducts capable of being used as reducing agents for metal ions. “Borane containing reduction resin” is used in the present specification and claims to mean the full collection of such resins.

SUMMARY OF THE INVENTION

The present invention is directed in overall theme to the use of the differential precipitation characteristics of SQAS with PGM and the extraction capabilities of the boron containing reduction resins to yield an enhanced powerful method of PGM refining. Separate aspects of the present invention include enhanced loading, chemical stripping and regeneration of the resins, recovery of SQAS, the use of hydrogen as a refining step, and other specific separation steps detailed below. Further, combinations of such separate aspects are contemplated to greater advantage in refining and purifying PGM. Particularly, each of the processes of removing concentrations of BM from PGM, refining Pd, Pt and Ru from SQAS bonded metals using H₂ and recycling the precipitated residual PGM to the refining of PGM and the concentrated SQAS to the refining reagent in solution may be combine with one or both of the other two as inventive subject matter.

Accordingly, it is a principal object of the present invention to provide an enhanced refining process for PGM. Other and further advantages will appear hereafter.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a processing diagram for Stage I, initial separation and base metal (BM) removal.

FIG. 2 is a processing diagram for Stage II, Pd recovery.

FIG. 3 is a processing diagram for Stage III, Pt and Rh recovery.

FIG. 4 is a processing diagram for Stage IV, Ru, Au, Ag recovery.

FIG. 5 is a processing diagram for Stage V, SQAS recovery and purification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Although many feeds would be suitable for this process, refining of PGM is usually conducted in hydrochloric acid. Hereafter it will be understood that although hydrochloric acid is described, other acids such as HBr and the like could be used.

Stage I

Antimony, bismuth, tin, phosphorus, selenium, and tellurium are known to co-precipitate with iron when the solution is made alkaline. Early removal of Sb, Bi, SN, P, Se, Te along with gold, ruthenium, silver, and lead from acid solutions of PGM is, therefore, conveniently achieved by simple pH adjustment as indicated in Stage I-3. To minimize acid and base consumption, it is efficient to remove most of the original solvent by distillation. Such distillation can be carried out with the usual distillation equipment familiar to those skilled in the art. Distillation may be carried out at atmospheric pressure or under a vacuum of 1-30″. Surprisingly, removal of acid by distillation achieves the first PGM separation. Osmium reports to the distillate in over 70% yield with purity exceeding 98% as indicated in Stage I-2. Osmium can be further refined by those skilled in the art. For example, neutralization of the solution followed by addition of gaseous chlorine. Osmium is carried out of solution as a gas and captured by a sodium hydroxide trap.

As indicated above, initial removal of bulk acid in the PGM is accomplished by distillation. Then, water and bases such as NaOH, KOH and the like are added. Dilution with water alone is also an option. The strength of the NaOH solution can be 0.1-50% or more, with 2.5-5% being most convenient. The pH desired varies depending on the element mix from 0 to 5, with 1.0 to 2.0 being most common. PGM rich solution, I-12, and a residue, I-6, are generated in this manner. Table I shows such a solution and residue with mg of metals contained. Table II shows the assay in ppm of such a solution before and after pH adjustment.

Table I, Ru and Au are quantitatively precipitated. Ag, As, Se, and Te are nearly completely precipitated. Substantial amounts of Fe are precipitated as well. Residue I-6 can be re-dissolved in dilute acid and re-precipitated with base to liberate the small amount of entrained PGM.

TABLE I Effect of NaOH addition Pt Pd Rh Ir Ru As Se Te Ag Fe Au solution (mg) 13,663 32,176 950 22 0 51 125 4 19 4,284 1 Residue (mg) 359 226 813 10 48 214 1,525 1,124 122 9,114 324

Table II shows solution assays before and after pH adjustment. Again, nearly quantitative precipitation of As, Au, Ag, Se, and Te is observed. In this case, however, Ru is only partially precipitated. Typically Se, Te, and Ru are not quantitatively removed by solvent removal alone if they are present is large amounts. “Large amounts” vary from a few hundred ppm to many thousands of ppm depending on the element. Practically, any concentration greater than 500 ppm may show less quantitative precipitation and require further base addition to achieve removal. Residues obtained in this manner will co-precipitate some PGM. Such residues may then be heated with water or dilute acid to extract nearly all the PGM as shown in Table III.

TABLE II pH increase to remove many base metals Original/Original + NaOH Pt Pd Rh Ru Ir Initial solution 79,552 51,757 37,894 22,014 10,880 Residue 249 125 345 7,549 142

TABLE III Residual PGM (mg) in pH adjusted (pH = 1.3) residue Pt Pd Rh As Ir Au Ag Ru Cu Fe Se Te 18,613 12,110 8,866 1,796 2,546 418 332 5,151 8,245 8,236 254 372 17,893 11,509 8,412 107 2,239 0 14 3,054 8,267 2,719 1 0

Since most of the Pt, Pd, Rh, and Ir are removed from the residue by the water wash, extraction into the soluble fraction, I-12, exceeds 99% for all four metals.

Large amounts of Ru are retained in the residue where it can be efficiently extracted in Stage IV. However, significant amounts of Ru are still in the aqueous extract. Increasing pH further can precipitate nearly all the ruthenium. Removal of acid by distillation is not adequate for this step. Moreover, Ru may be removed from neutral solutions throughout the flow sheet by simply bubbling chlorine through the solution. This is particularly useful if there is trace contamination of Ru in Rh-SQAS or similar Pt, Pd, Ir species. It also applies at this juncture in which all Ru can be removed from solution I-12 using this technique. This generates a Ru free solution to be presented to the resin and eliminates any Ru downstream of this step.

Solution I-12 is then passed over a borane containing resin described by Manziek in the US patents above. These types of resins have been used to recover PGM before as a scavenger but are unknown as a pivotal component in a refining scheme. However, the resin has many remarkable abilities that should be used in this venue. The resin rejects alkali and alkali earth metals meaning that all the sodium generated in the pH adjustment is not passed into the refining circuit. Furthermore, the resin rejects nearly all transition metals as well. Finally, the loading capacity of these resins are 50-100 times greater than conventional resins.

In the past these borane containing resins were burned to recover metal since the resin is a reductive resin and metals are present as reduced metal. Surprisingly, the resin can be stripped of precious metals chemically using halogens, hydrogen peroxide, oxygen and other oxidizers rather than by burning the entire body of resin. The very surprising ability of oxygen gas to dissolve PGM occurs at pressures of 1-1000 psi at 1-150 C with 50 psi and 90° C. being convenient. Table IV below shows the results of oxygen stripping of 4 grams of partially loaded resin. Oxygen pressure was 50 psi, temp. 90° C. for 18 hours.

TABLE IV Oxygen stripping of resin Pt Pd Rh Ag Ru Cu Ni Fe solution (mg) 417 782 6 1 1 6 0 1 Ash (mg) 1 After oxygen treatment, the resin was washed with hot 6N HCl. Residual resin was burned at 600 C and one mg of ash was recovered. Therefore, total PGM recovery exceeded 99.9%. Further, chemically stripped resin is capable of regeneration, a totally new result that reduces cost. Unexpectedly, the resin does load ruthenium, contrary to the understanding of Manziek in the US patents above.

Finally, the resin can be washed of the boron generated in metal loading and other spurious metals before metal re-dissolution leading to a very pure PGM feed when compared to feeds usually found in a precious metal refinery. Such an initial purity is a great advantage since many base metal/PGM separations found in refineries today are totally eliminated. This reduces steps and related capital and operating costs.

Conditions necessary for loading PGM is pH in the range of 0-8. Manziek quotes a narrower range of 1-8, but the resin is effective in more acidic solution than reported. Further, it is advantageous to heat the solutions in contact with the resin. Rhodium and iridium load very slowly if not heated. Also, heating speeds loading of all metals and reduces loading time from several hours to about an hour, further reducing costs. Finally, metals loaded on the Manziek resin are slowly stripped under normal atmospheric conditions. Use of nitrogen atmosphere totally eliminates this stripping and maximizes loading of all precious metals on the resin. Table V below shows the efficiency with which resin quantitatively loads PGM.

TABLE V Loading of PGM on resin Pt Pd Rh Ni Cu Initial solution 8,300 16,000 1600 48,000 5,000 Residual 0 1 4 48,000 5,000 solution PGM load while base metals contained in Solution I-13 are rejected. Once loaded, the PGM are washed with dilute HCl, and then stripped of precious metals using oxidizing agents such as chlorine, hydrogen peroxide, and remarkably, oxygen gas or any other reagent that dissolves metallic PGM. Oxygen may be pressurized to increasing stripping efficiency. After oxidation, the beads are subjected to repeated strips with hot acid at 30-150° C., with 109° C. being convenient. Extraction with 6N HCl works quite well. Other strips such as ammonia or complexing agents could be used after the oxidation step. The oxidation liquor is combined with the stripping extract to form Solution I-16. Some copper and lead will load on the borane resin will report to the strip Solution I-16. Solvent removal followed by water dissolution generates a solution that has cationic lead and copper and can be readily removed by strong cation exchange resins such as USF 211 and others well known for this ability. Purolite S950, a chelating resin also removes tramp metals, as would many other resins. STAGE II.

Once a PGM solution with very low levels of base metals is achieved, refining of the PGM proceeds in a locked cycle as shown in Stages II, III, IV, and V. Stage II begins with a reflux of the PGM solution with hydrochloric acid, NaCl and SQAS as shown in FIG. 2, Stage II-2. Hydrochloric acid may vary from 1% to 37% or more, SQAS concentration may vary from 1% to 30% or more and NaCl concentration can vary from 0.1% to 20% or more. A convenient initial ratio of HCl:SQAS:NaCl:water is 10:40:3:47. This mixture is refluxed at atmospheric pressure for 0.5 to 24 hours, 8 hours being typical.

Example

-   -   Mix the following in a 20 liter flask:     -   3500 grams SQAS     -   4500 grams 6N HCl     -   80 grams of PGM in solution     -   Stir while refluxing the solutions at about 110 C for about 8         hours.     -   The mixture was cooled to room temperature and filtered to yield         Solid II-3 and Solution II-5.

Solid II-3 is washed with the solution described as II-4. All washings report to Solution II-5 that contains nearly all the palladium and small amounts of other metals. Solution II-5 has a typical ppm analysis of 57, 2983, 10, I72, 58 ppm for Pt, Pd, Rh, Ir, Ru, respectively. Oxidation of Solution II-5 with species such as halogens and the like generates a solid precipitate of crude Pd-SQAS, Stage II-8. The residual solution, II-7, reports to Stage V. Solid II-3 reports to Stage III.

Example

-   -   6800 grams of Solution II-5 is treated with chlorine gas for         about 1 hour. Reaction with palladium is stoichiometric.         Approximately 200 grams of damp Pd-SQAS was obtained by         filtration. This solid is washed with about 2 liters of water         saturated with chlorine. Filtrate is routed to Solution II-7.         Slurring with about 400 ml of water and heating to reflux         further processes Solid II-8. Chlorine gas is evolved. Small         amounts of Ru and Os, possibly present, will be largely removed         as ReO₄ and OsO₄ gas in the chlorine. The resulting solution,         II-13 is treated with enough reducing agent such as hydrogen gas         to convert about 5% of the Pd to metallic form as shown in Stage         II-12. Enough 1% Na₂S is added to convert about 1% of the         palladium to PdS. The resulting slurry of Pd, PdS and soluble Pd         and other contaminate metals are refluxed overnight. This         process removes Pt and most other contaminants as insoluble         species. Filtration removes Solid II-14, which is sent to the         initial PGM dissolution step. The residual solution, II-15, is         reduced to high purity metal with hydrogen gas. Conditions are         1-1000 psi hydrogen at 25-150° C. with 15 psi and 90° C. being         convenient. Acid content may be neutral to 6N or higher. Final         Pd purity exceeds 99.9%. Residual Solution II-16 is pure SQAS in         HCl and may be used directly in steps requiring high purity SQAS         washes or may be combined into Stage V.

Reduction of metals such as palladium with hydrazine or similar reagents is not desirable. Hydrazine as usually employed renders SQAS unstable and causes decomposition into species that are not suitable for precious metal recovery and destroy the possibility of recycling SQAS. Use of hydrogen is further advantageous because it adds no foreign substances to the reduction byproducts thereby enabling simple recycling of SQAS. Many other reducing agents leave behind reduction byproducts that complicate and even render impossible the recycling of SQAS. Hydrogen is also a mild reducing agent that does not reduce most base metals under the conditions used. Therefore, hydrogen reduction is a purification step that eliminates many base metals from the final palladium metal product. Although hydrogen reduction of PGM is well known, it has not been used as refining reagent as proposed here.

Stage III

FIG. 3 shows the steps for preparing high purity Pt and Rh from Solid II-3. First, the solid is stirred with acid of concentration 0.1-100%, containing 0.1-10% SQAS. Many acids would suffice, but 6N HCl containing 2% SQAS is convenient. Pt-SQAS is relatively insoluble in this mixture. Pt-SQAS, may be removed by filtration yielding Solid III-3 and Solution III-10 containing soluble Ir, Rh, SQAS, HCl, and trace amounts of Pt. Solid III-3 is washed with a mixture of acid and SQAS. SQAS concentration may vary from 0-50% and acid content may vary from 0-50% with a solution of 20% HCl and 20% SQAS in water being most convenient. The resulting filtrate is routed to SQAS recovery, Stage V.

The washed crude Pt-SQAS is dissolved in boiling solvent, which may be water or acid. Hydrochloric acid, 6N, is conveniently used. Approximately 0.14 Kg Pt-SQAS will dissolve in 1 liter of boiling 6N HCl. This is filtered hot and allowed to crystallize after adding 0.1-50% SQAS to the hot liquid with the equivalent of 3% SQAS being convenient. Resulting crystallized Pt-SQAS is washed with the same mixture of 6N HCl and 20% SQAS to yield a product Pt-SQAS that is about 99.9% pure. Further increases in purity are achieved by repeating the recrystallization step.

Pt metal is obtained by slurring Pt-SQAS in water using the conditions described for Pd metal. Pt metal precipitates and more Pt-SQAS dissolves in water until the entire mass of Pt-SQAS has been dissolved and reduced. Therefore, the volume of solute required for hydrogenation can be relatively small since the Pt-SQAS present in the slurry constantly dissolves as hydrogen depletes the soluble platinum by reduction to insoluble metal. This leads to smaller hydrogenation vessels and smaller filtrate volume for III-9. Fortunately, the very high solubility of SQAS allows SQAS to accumulate in solution creating a very concentrated SQAS solution very suitable for many of the washing steps needed elsewhere in the flowchart. The resulting Solution III-9 is high purity SQAS in acid and may be retained for future washes requiring high purity SQAS or sent to Stage V.

Solution III-10 contains rhodium and iridium. Iridium is separated from rhodium by chlorinating the solution at room temperature for a period of a few minutes to several hours, two hours usually being satisfactory. Filtration yields Solid III-12, crude Ir-SQAS and Solution III-13 containing rhodium. Crude Ir-SQAS is refined as described in U.S. Pat. No. 7,935,173.

Rh-SQAS is precipitated from Solution III-13 by distilling off solvent. 1-90% of the solvent may be removed, with 70% removal being convenient. Filtration yields Solid III-15, crude Rh-SQAS, which is washed with a mixture of acid and SQAS. SQAS concentration may vary from 0-50% and acid content may vary from 0-50% with a solution such as III-17, composed of 20% HCl and 30% SQAS in water, being convenient.

Solid III-15 is then dissolved in HCl of composition 0.1-40%, with 20% being convenient. Sufficient SQAS is added to comprise 1% of the mass and chlorine is bubbled through the solution for a few minutes to several hours, with 2 hours usually being sufficient. Filtration yields Solution III-19 results along with Solid III-20. Solid III-20 can be returned to Stage II-1. Solution 19 is distilled to remove solvent and water added to replace the acid. If there is any residual Ru in III-22, bubbling chlorine through this solution for 0.5-20 hours with 2 hours being typical removes all Ru.

Subsequently, sufficient Na₂S to precipitate 1-5% of the rhodium with 2% being convenient is added to Solution III-22. The slurry is then refluxed for 0.1-24 hours, with 8 hours usually being sufficient. Filtration yields Solution 111-22 and solid 21. Solid 21 is recycled to the original dissolution of PGM. Solution III-22 is high purity rhodium. Solution 22 is then treated with hydrogen gas as described for palladium and metal of 99.9% purity or better results. Filtrate III-24 is high purity SQAS in solution and may be used directly or sent to Stage V.

Stage IV

Ruthenium can advantageously be removed from Residue IV-1 by addition of water to form a slurry and injection of gaseous chlorine. RuO₄ is volatilized as a gas and can be trapped with a hydrochloric acid trap as is well known to those skilled in the art. Purity is 99.5%. Filtration and washing the residue with water generates Solution IV-5 and Solid IV-4. Silver reports quantitatively to IV-4. Washing IV-4 with dilute HCl removed entrained PGM that can be added to Solution IV-9. Resulting Solid IV-11 contains silver and other tramp metals that may be refined for silver by methods well known to those skilled in the art.

Gold reports quantitatively to Solution IV-5. Gold can be recovered by many methods known to those who practice the art. For example, Solution IV-5 may be acidified and passed over XAD-7 resin. Gold is captured and may be recovered and precipitated as detailed in many publications (A Filcenco et al. CHem. Bull. “Politehnica” Univ. 53(67)1-2, 2008.) Residual Solution IV-9 is sent to Stage I-1.

Stage V

Recycling SQAS and minor amounts of PGM contained in washes and filtrates are remarkably simple. All PGM are conserved and clean SQAS is recovered. Many routes for recycling are possible and one of them is outlined in Stage V. SQAS, HCl, NaCl, and minor amounts of metals are the only species in any of the PGM solutions generated in this process. The unique ability to refine all precious metals with a single precipitant allows all PGM containing solutions in Stages II, III, and IV to be combined into a single vessel, an unprecedented ability. Volume may be reduced as indicated by V-2 using distillation so that some hydrochloric acid is driven off. This leaves a very concentrated solution of SQAS in which PGM are insoluble. Since most of the PGM are least soluble in their highest oxidation state, oxidation may be executed before filtration to minimize residual PGM in the SQAS solution. Often oxidation is unnecessary as the PGM are sufficiently insoluble without oxidation. PGM concentrations in V-6 are typically single or double-digit with occasional triple digit ppm. Residue V-5 is recycled to the beginning of the PGM refining circuit, II-1.

At this point, many options are available to remove the small amounts of metals present in Solution V-6. All subsequent treatment begins with removal of hydrochloric acid by distillation with or without vacuum, vacuum being preferred since lower temperatures of distillation are required. Water is added to completely dissolve SQAS and filtration removes small amounts of insoluble giving Solution V-11. Cleanup routes 13, 14, or 15 may be used individually or in combination. Ion exchange, route 13, will remove all or most of the metals to very low values. Cation exchange resins are routinely used to remove base metals from solutions as is well known to those skilled in the art (U.S. Pat. No. 6,551,378). Similarly, anion exchange resins have been used to remove PGM and other metals from solutions (Desalination and Water Treatment, 45, p. 2012; Analytical Sciences, 19, pp 1621-24 (2003). Route 14 precipitates insoluble metal sulfides removed by filtration. Recommended dosage is stoichiometric so that no residual free sulfide is left in the system. Route 15 reduces soluble metal ions to insoluble metals by reduction. Hydrogen, NaBH4, and other reducing agents can be employed. Solutions generated by reduction of pure PGM-SQAS salts such as Solutions II-13, III-9, and III-20 are already high purity SQAS and require no treatment.

Example

-   -   A composite of Solutions II-6, II-5, III-16 and others were         combined to yield 821 grams of solution. An immediate         precipitate was observed. Filtration yielded 12.5 grams of damp         solid containing Pt, Pd, Ir, Ru and copper. ICP revealed that         the relative ratio of elements were 90:480:5:5:10 respectively.         The residual solution was heated in a 140° C. oil bath to remove         solvent until no further distillate was observed. The solution         was cooled to room temperature and filtered. The residue was         combined with the 12.5 grams originally recovered and returned         to Stage II-1. The filtrate was analyzed for Rh, Pt, Pd, Ir, Ru,         Cu, Fe and the relative values in ppm were 0, 15, 241, 19, 37,         467, and 7. An equal volume of water was added and the mixture         chlorinated at room temperature for one hour. Precipitates         formed were removed by filtration yielding a solution containing         0, 0, 0, 5, 32, 384 and 8 ppm, respectively. 0.4 gram of NaBH₄         was added to the mixture with stirring and yielded a solution         that assayed 0, 0, 2, 2, 4, 0 and 0 ppm. The resulting SQAS         solution was sufficiently pure for reuse.

Thus, a process for the refining of PGM from PGM and BM is disclosed. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore is not to be restricted except in the spirit of the appended claims. 

1. Removing concentrations of base metals (BM) from platinum group metals (PGM) comprising dissolving any of BM and PGM in an acidic aqueous solution; precipitating the BM by increasing alkalinity in the aqueous solution; loading the PGM on borane containing reduction resin from the aqueous solution as metal; stripping the PGM from the resins using oxidizing agents.
 2. The process of claim 1 further comprising distilling a large fraction of the aqueous solution before increasing alkalinity in the aqueous solution.
 3. The process of claim 2 further comprising recovering Os from the distillate.
 4. The process of 3 claim 1, loading the PGM on resin being in an inert atmosphere.
 5. The process of claim 1, stripping the PGM from the borane resin through oxidation being with gaseous oxygen.
 6. Removing concentrations of base metals (BM) from platinum group metals (PGM) comprising dissolving any of BM and PGM in an acidic aqueous solution; distilling a large fraction of the aqueous solution before increasing alkalinity in the aqueous solution; precipitating the BM by increasing alkalinity in the aqueous solution; heating the aqueous solution following precipitation of the BM; loading the PGM on borane containing reduction resins from the heated aqueous solution; washing the loaded resins; stripping the PGM from the resins with gaseous oxygen.
 7. The process of claim 6 further comprising recovering Os from the distillate.
 8. The process of claim 6, loading PGM on resin being in an inert atmosphere.
 9. Refining at least one platinum group metal (PGM) from substituted quaternary ammonium salt (SQAS) bonded metal, comprising preparing a neutral to acidic PGM-SQAS solution; reducing the PGM from the solution with H₂.
 10. The process of claim 9, preparing the neutral to acidic PGM-SQAS solution including refluxing PGM with SQAS and HCl, oxidizing the refluxed solution with halogen to obtain a PGM-SQAS precipitate, refluxing the PGM-SQAS precipitate in boiling water to the neutral to acidic PGM-SQAS solution.
 11. The process of claim 9, the neutral to acidic PGM-SQAS solution being a slurry.
 12. The process of claim 9, the PGM being one of Pd, Pt or Rh.
 13. The process of claim 9 further comprising separating the PGM-SQAS by individual elements of PGM-SQAS before reducing the PGM from the solution with H₂.
 14. A process fro refining PGM comprising refining PGM using SQAS as the refining reagent in solution; separating each refined PGM from the refining reagent solution; combining all refining reagent solutions together; precipitating residual PGM; recycling the precipitated residual PGM to the refining of PGM; recycling the concentrated SQAS as the refining reagent in solution.
 15. The process of claim 13, precipitating residual PGM including removing solvent from the combined refining reagent in solution. 